Abstract: The water samples obtained in different water layers of a reservoir and inplugs of water pipes were collected for the investigation of Fe-Mn oxidized sheathedbacteria The bacteria were found in plugs and the layers where the organic nutritionwas considered low. It is indicated that the best seasons for the growth of bacteriaare summer and autumn, and the suitable growing place is in the lower layer andbottom of the reservoir where the temperature is 21-25℃, pH 6.16-6.87 Fe 0.43mg / L, and oxygenic concentration is low. The selective media with limitednutrient concentrations and enriched culture were used for isolation of the bacteria.The results showed that urea-glucose-inorganic salt medium and Stokes medium aresuitable for the enrichment of the sheathed bacteria and Winogradsky iron bacteriamedium and Muder managanese medium are more effective for the enrichment andisolation of Fe-Mn oxidized sheathed bacteria. The addition of 0.5u/ml of sodiumpenicilline in the medium can increase the growth rate of Fe-Mn oxidized sheathedbacteria CGY medium can be used to purify the bacteria; Two strains of Fe-Mnoxidized sheathed bacteria,FC9771-1 and FC9771-2, were finally purified. Accordingto their morphological and culture features, FC9771-1 was preliminarily identified asgenus in the Sphaerotilus, FC9771-2 as Leptothrix genus.